Immunity - antibodies

Question 1

What are monoclonal antibodies

Answer 1

(Identical) Antibodies from cloned B-cells

Question 2

What does the specificity of an antibody depend on?

Answer 2

-The specificity of an antibody depends on the variable region which forms the antigen binding sites
-Each antibody has a variable region with a unique tertiary structure ( due to different amino acid sequences )
-The unique tertiary structure is complimentary to an antigen

Question 3

What are antibodies

Answer 3

Proteins - they’re made up of chains of amino acids

Question 4

What is the function of plasma cells?

Answer 4

-Identical to B-cells, secrete lots of antibodies specific to the antigens (monoclonal antibodies)

Question 5

How can antigens help in destroying pathogens ?

Answer 5

-An antibody has two binding sites, so can bind to two pathogens at the same time
-This means that the pathogens can be clumped together (agglutination)
-This makes phagocytosis easier as many pathogens can be destroyed at the same time

Question 6

Describe the ELISA test?

Answer 6

-Apply sample to a slide, to which all the antigens in the sample will attach
-Wash the surface several times to remove any unnattached antigens
-Add the antibody that is specific to the antigen we are trying to detect, leave to bind together
-Wash surface to remove excess antibody
-Add second antibody which binds to first. This has enzyme attached
-Add colourless substrate ( enzyme acts on the substrate to change it into coloured product )
-Amount of antigen present is relative to intensity if colour which develops

Question 7

State ethical issues using monoclonal antibodies

Answer 7

-Animals are used to produce the cells from which the monoclonal antibodies are produced
-Testing on people can have serious side affects

Question 8

How can monoclonal antibodies be used to treat cancer?

Answer 8

-Cancer cells have tumour markers not found on normal cells
-Monoclonal antibodies can be made to bind to these tumour markers
-You can also attach tumour markers to the monoclonal antibodies
-so when antibodies come into contact with cancer cells they will bind to tumour makers
-Anti cancer drug will accumulate near cancer cells, so side effects less than other drugs

Question 9

How can monoclonal antibodies be used to detect a specififc antigen e.g. pregnancy test?

Answer 9

-application area contains antibodies for hCG antigen, bound to coloured bead
-when urine applied, any hCG will bind to the antibody on the bead, forming an anitgen-antibody complex.
-urine moves up stick to test strip, carrying any beads w/ it
-test strip contains antibodies to hCG whic are immobilised
-if hCG present, the test strip turns blue as as immobilised antibody beinds to hCG